Hyperbolic paraboloids are solutions of the equation \(\frac{x^2}{a^2}+\frac{y^2}{b^2}-\frac{z^2}{c^2}=1\) with \(a,b,c\) positive reals. For \(a=b\) the surface can be generated as a surface of revolution of a hyperbola or of two lines (model 24).>>